Mitsubishi Montero Sport (2004+). Manual - part 232

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-341

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CIRCUIT OPERATION

• A voltage corresponding to the oxygen concen-

tration in the exhaust gas is sent to the PCM (ter-
minal No. 73) from the output terminal (terminal 
No. 4) of the left bank heated oxygen sensor 
(rear).

• Terminal No. 2 of the left bank heated oxygen 

sensor (rear) is grounded with PCM (terminal No. 
57).

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TECHNICAL DESCRIPTION

• The output signal of the left bank heated oxygen 

sensor (front) is compensated by the output sig-
nal of the left bank heated oxygen sensor (rear).

• The PCM checks for an open circuit in the left 

bank heated oxygen sensor (rear) output line.

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AK200497

LEFT BANK
HEATED OXYGEN
SENSOR (REAR)

E-48(B)

AB

CONNECTOR: E-48

AK103738AE

CONNECTORS: C-90, C-91

PCM

C-91(GR)

C-90(GR)

AK200018 AB

CONNECTOR: E-44

E-44

AK103912AB

CONNECTOR: C-71

C-71

AK103911AC

CONNECTOR: C-79

C-79

AK200018 AC

CONNECTOR: E-45

E-45(B)

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-342

DESCRIPTIONS OF MONITOR METHODS
Left bank heated oxygen sensor (rear) output voltage 

stays low when air/fuel ratio is forced to be rich. 
The above procedure is repeated when oxygen 
sensor is inactive.

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MONITOR EXECUTION
Continuous

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MONITOR EXECUTION CONDITIONS (Other 
monitor and Sensor)

Other Monitor (There is no temporary DTC stored 

in memory for the item monitored below)

• Heated oxygen sensor heater (front) monitor

• Heated oxygen sensor heater (rear) monitor

• Air/fuel ratio feedback monitor

Sensor (The sensor below is determined to be 

normal)

• Volume airflow sensor

• Engine coolant temperature sensor

• Intake air temperature sensor

• Barometric pressure sensor

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MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-343

DTC SET CONDITIONS

Logic Flow Chart

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START

V

F

 > =4.5V

2secs HAS PASSED

YES

YES

YES

NO

NO

NO

MALFUNCTION

MONITORING

CONDITIONS

YES

NO

MONITORING

CONDITIONS

+5V ON

AK301440

V

F

 < 0.15V

10secs HAS PASSED

YES

YES

NO

NO

END

MALFUNCTION

GOOD

MODULATE A/F CONDITION TO RICH

MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-344

Check Conditions

• 3 minutes or more have passed since the starting 

sequence was completed.

• Left bank heated oxygen sensor (rear) signal volt-

age has continued to be 0.15 volt or lower.

• Engine coolant temperature is higher than 76°C 

(169

°F).

• Engine speed is higher than 1,200 r/min.

• Volumetric efficiency is higher than 25 percent.

• Volume airflow sensor output frequency is 100 Hz 

or more.

• At least 20 seconds have passed since fuel shut 

off control was canceled.

• Monitoring time: 10 seconds.

Judgement Criteria

• Making the air/fuel ratio 15 percent for 10 sec-

onds richer does not result in raising the left bank 
heated oxygen sensor (rear) output voltage 
beyond 0.15 volt.

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OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function 

− OBD-II Drive Cycle − 

Procedure 6 

− Other Monitor 

P.13A-4

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TROUBLESHOOTING HINTS (The most likely 
causes for this code to be set are:)

• Left bank heated oxygen sensor (rear) failed.

• Short circuit in left bank heated oxygen sensor 

(rear) output line.

• PCM failed.

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (MUT-III Sub Assembly)

• MB991824: V.C.I

• MB991827: USB Cable

• MB991911: Main Harness B

• MB998464: Test Harness Set

STEP 1. Using scan tool MB991958, check data list item 59: 
Heated Oxygen Sensor Bank 2, Sensor 2 (left bank).

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Start the engine and run at idle.
(3) Set scan tool MB991958 to the data reading mode for item 

59, Heated Oxygen Sensor Bank 2, Sensor 2 (left rear).

• Warm up the engine. When the engine is revved, the 

output voltage should repeat 0 volt and 0.6 to 1.0 volt 
alternately.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?

YES : It can be assumed that this malfunction is intermittent. 

Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

P.00-7

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NO :  Go to Step 2.

AK303629AB

MB991911

MB991827

MB991824 

16-PIN